It helps to speak right onto the recording while doing it, if you see a species or suspect it is a certain species.  When there are a lot of sounds, when you play it back it is confusing, and that can help.  Use the directionality of the mic to focus on one individual bird at a time, and then turn to the other side.  Also, speak on the recording of what other birds are singing and exactly where your location is.  It is easy to forget where you were.  You can delete your voice later.  Go back to the same locations again.  Use your binoculars and don't record, sometimes, you may see birds that you miss while concentrating on the recording equipment. It takes lots of experience to identify birds by sound, and I have been doing it since I was 7 and now I am 72.  It is so much fun.  I am really impressed with the recordings on my smartphone, they are just as good as my Marantz 661 and Sennheiser microphone.   Good luck!  -  Linda.

Hi, Maybe you can use software to reduce the noise in your omnidirectional recordings. Ocenaudio and WattPad (free versions available) can reliably remove low and/or high-pitched sounds, in my experience. There is still often some noise left, though. Alternatively, improvise a parabolic directional mike - search YouTube for "how to make a parabolic mike". For surveys, can you combine a number of directional recordings into a standardized sampling protocol - same number of recordings, for the same number of seconds or minutes each, in the same compass directions, at each time/location? If you can validate your sampling as being reliable enough to estimate total population at each time/place, it may be good enough. Just some ideas.